1. Field of the Invention
The invention relates to an aftertreatment apparatus for effecting an aftertreatment on paper sheets, and a controlling method, a program and a storage medium therefor.
2. Description of Related Art
Generally, an image forming apparatus such as a copying machine has connected thereto a finisher or the like for effecting an aftertreatment such as a staple treatment or bookbinding on sheets having images formed thereon. For example, in the staple treatment, a stapler is driven and a sorted sheet bundle is stapled.
Also, in recent years, a finisher provided with an inserted sheet feeder for supplying an inserted into a bundle of sheets having images formed thereon has made its appearance (see Japanese Patent Application Laid-Open Nos. S60-180894, S60-191932 and S60-204564). In such a finisher, an inserted sheet is supplied from the inserted sheet feeder into the finisher at predetermined timing, and is conveyed to an intermediate tray in the finisher. Then, the inserted sheet is stacked on sheets from the image forming apparatus stacked on the intermediate tray. Here, sheets including the inserted sheet are stacked on the intermediate tray so as to be in the order of pages and the predetermined timing at which the inserted sheet is supplied is such timing that the inserted sheet assumes a corresponding page position in the sheet bundle.
Also, in order to cope with a case where originals more than a predetermined maximum number of bound sheets are read and a staple treatment is effected on a bundle of the sheets having images formed thereon, there is an image forming apparatus provided with a divisional staple mode for dividing the sheets by each predetermined number of sheets and binding them.
As an inserted sheet such as a cover sheet or a slip-sheet supplied from the inserted sheet feeder, use is often made of a sheet thicker than sheets on which images are formed in the image forming apparatus. Also, in a case where there are a plurality of inserted sheet feeders, it is supposed that sheets having various sheet thicknesses are fed from the respective inserted sheet feeders. Consequently, in a case where a maximum number of sheets capable of being stapled are predetermined and sheets of different thicknesses are mixedly present in a sheet bundle, even if the number of sheets is within the maximum number of sheets capable of being stapled, the thickness of the sheet bundle sometimes exceeds a thickness capable of being stapled. In such case, staple needles may be buckled and the dignity of binding may become bad, and the needle jam of the stapler may occur and as a result, a faulty aftertreatment may occur.
Also, in the case of a pre-divisional staple mode, if sheets inserted sheets supplied from the inserted sheet feeder are likewise mixedly present in a sheet bundle, a sheet bundle having a predetermined number of sheets sometimes exceeds a thickness capable of being stapled, and the buckle or jam of staple needles may occur.
To avoid such inconvenience, it is desired, for example, to measure the thickness of the sheet bundle at real time, and effect, for example, divisional staple treatment or the like with an appropriate thickness of the sheet bundle.
Also, when a punch treatment is to be effected in the finisher, even if in the case of a bundle sheet in which sheets of different thicknesses are mixedly present, the number of sheets is within a maximum number of sheets capable of being punched, the thickness of the sheet bundle sometimes exceeds a thickness capable of being punched as in the case of the already described stapler treatment.
In Japanese Patent Application Laid-Open No. 2003-1910, it is disclosed to judge from the thickness of a bundle of sheets calculated by calculating means whether the staple treatment is possible in an image forming apparatus having an operating panel for setting the condition of the sheets, and calculating means for calculating the thickness of the bundle of sheets to be staple-treatment from the condition set by the operating panel. Japanese Patent Application Laid-Open No. 2003-1910, however, merely discloses a construction in which sheets on which images are to be formed are set by the operating panel. Consequently, it cannot cope with a sheet inserted into sheets having images formed thereon. Further, in the apparatus of Japanese Patent Application Laid-Open No. 2003-1910, the thicknesses of the sheets are selected by the operating panel. Consequently, the apparatus of Japanese Patent Application Laid-Open No. 2003-1910 is established as an apparatus on the premise that the thickness of the sheets are all found prior to the setting by the operating panel. Accordingly, the apparatus of Japanese Patent Application Laid-Open No. 2003-1910 cannot cope with a case where it is difficult for the thicknesses of sheets to be found in advance, that is, a case where various types of sheets are used.
In Japanese Patent Application Laid-Open No. H2-38262, there is described a sheet aftertreatment controlling apparatus which is provided a gripper for nipping and conveying a sheet bundle, and means provided on the gripper for detecting the thickness of the sheet bundle nipped by the gripper, and which does not perform a stapling operation when it is judged that the thickness of the sheet bundle has exceeded the limit thickness bundle has exceeded the limit thickness capable of being stapled. In the construction described in Japanese Patent Application Laid-Open No. H2-38262, much time is required for nipping the sheets of a bundle shape by the gripper, and this leads to a problem in respect of an improvement in productivity.
In Japanese Patent Application Laid-Open No. 2000-184154, it is disclosed to detect the thicknesses of respective recording mediums and accumulate these thicknesses to thereby find the width of the spine of a sheet bundle when bookbound. In Japanese Patent Application Laid-Open No. 2000-184154, however, to find the width of the spine is in order to determine the image positions of the cover and spine, and no description is made of a problem attributable to the above-noted maximum number of sheets capable of being stapled or the maximum number of sheets capable of being punched. Saying in addition, the construction of Japanese Patent Application Laid-Open No. 2000-184154 detects the thicknesses of the recording mediums (sheets) on which images are recorded, and does not cope with the thickness of a sheet inserted into sheets having images formed thereon.